Improvement in mariners  compasses



D. BAKER.

Mariners Compass Pa tented June I, 1875.-

THE GRAPHIC 60. PH 0T0 -LlTH-39 8; 41 PARK PLACE, NAV.

UETTED STATEs PATENT OFF-ICE.

DAVID BAKER, OF BOSTON, MASSACHUSETTS, ASSIGNOR OF ONE-HALF HIS RIGHT TOWILLARD I. HUMPHREY, OF SAME PLACE.

IMPROVEMENT IN MARINERS COMPASSES.

Specification forming part of Letters Patent No. 163,838, dated June 1,1875 application filed October 21, 1874.

OAsE B.

To all whom it may concern:

Be it known that I, DAVID BAKER, of Boston, in the county of Suffolk andState of Massachusetts, have invented certain new and usefulImprovements in Mariners Oompasses, of which the following is aspecification:

The nature of my invention consists in so constructing a marinerscompass that the axis of the outer gimbal-ring shall be in a line foreand aft of the compass-bowl sus pended therein; and-further in makingthe indicating-mark, known as the lubber-pdint, on one or both sides ofthe compass-bowl, and at a point in the direction of the said axis ofthe outer gimbal-ring, instead of being at right angles thereto, asheretofore constructed.

Mariners compasses heretofore have been constructed so that the axis ofthe outer gimbal-ring was at right angles to a line passing through theCOlllPLSSbOWl fore and aft, (when in use.) which line is represented bya mark or markson the inside of the compassbow], at a point fore or foreand aft, such mark being termed by mariners the lubber-point, and is theguide, in connection with the compass-card, used in steering.

By such construction of the axis of the outer gimbal ring, (when inuse,) as to be atliwart-ships or crosswise of the vessel, and having afixed support, it will be seen that whenever the vessel is heeled orinclined to either side the gimbal-ring. is also inclined, and while inthis position any pitching motion of the vessel, as she rises and fallsover the sea, causes the mark, called the lubber-point, on thecompass-bowl, to move out of line with the vessels direction, and thusmisrepre- Sent fl lllfiflll I m NM This erroneous indication of avessels course is a great stumbling-block to the mariner, and is oftenattended with danger, particularly in stormy weather when near thecoast, and is, doubtless, the cause of many disasters.

The object of my invention is to overcome these imperfections inmariners compasses; and I find, after many experiments, that with acompass constructed according to my invention, however much the vesselmay be heeled, her pitching motion, as she rises and falls over the sea,does not cause the so-called lubber point to move out of true line withthe vessels course or direction, but her course is as truly representedby such mark or point as when the vessel is sailing in the smoothestwater.

Figure 2 is a top plan view of a mariners compass constructed accordingto my invention, the card being omitted. Fig. 1 is a Vertical centralsection of the same at the point indicated by the dotted lines X Y, thelower portions being broken away.

A represents the compass-case of usual construction. B represents theouter gimbalring, and O O its journals or axismoving freely in bearingsD D affixed at opposite sides, and on the top edge of case A. Erepresents the compass-bowl, provided with pivots F F which have theirbearings in the gimbalring B, and at opposite sides thereof, being atright angles to the journals 0 O of gimbal-ring B. G represents a markor marks or other means of indicating a point or line in the directionof the axis of the outer gimbalring, or other equivalent means therefor.This point or mark I have indicated by one or more marks upon the insideof the compass-bowl, and at a point in the direction of the axis of theouter gimbal-ring, and at one or upon opposite sides of thecompass-bowl. A mark upon the top of the glass-plate, or on the top ofthe compass-bowl, or other means of indieating or designating thelubberpoint, socalled, located in the direction of the axis of the outergimbal-ring, would be sufficient to serve for the purposes contemplated.

Having thus described my invention, what I claim is 1. In a marinerscompass, a mark or marks or-other means of indicating a point or line inthe direction of the axis of the outer gimbal-ring, as and for thepurposes set forth.

2. A mariners compass provided with means for indicating thelubber-point, placed in the vertical pane of the axis of the outergimbal-ring, substantially as and for the pur pose set forth.

DAVID BAKER. Witnesses:

.SYLvENUs WALKER, GEO. A. BAKER.

